Quadrantal error corrector system



Sept. 28, 1943. w. P. LEAR QUADRANTAL ERROR CGRRIEICTOR SYSTEMS Filed Oct. 17, 1940 5 Sheets-Sheet 1 AUTOMATIC RADIO o.

DIRECTION FINDER F'IG.I.

FIG.3.

ATTORNEY.

W. P. LEAR QUDRANTAL ERROR CORRECTOR SYSTEMS Sept. 28, 1943.

Filed oct. 17, 1940 5 Sheets-sheet 2' FIG.4.

INDIGATOH INVENTOR.

BY @a/w TO LOOa A NTENNA ATTORNEY.

Sept. Z8, 1943.

w. P. LEAR QUADRANTAL ERROR CORRECTOR SYSTEMS Filed Oct. 17, 1940 5 Sheets-Sheet 3 1 INVENTOR. Qlam c6? Mea/r ATTORNEY.

Sept. 28, 1943. w. P. LEAR 2,330,226

QUADRANTAL .ERROR CORRECTOR SYSTEMS Filed Oct. 17, 1940 5 Sheets-Sheet 4 l, INVENTOR.

BY md. (amK ATTORNEY.

Sept. 28, 1943.

W. P. LEAR QUADRANTAL ERROR CRRECTOR SYSTEMS Filed Oct. 17. 1940 FIG. I 4.

5 Sheets-She'et 5 Patented Sept. 28, 1943 SYSTEM William P' Ler" Daytll, Ohio...A assigner.-v byi y mesne assignments,y to Lear Avia. Ohio, a,V corporation of Illinois l.

Inc..v Piqua,` l

Application october 17, 1940,-serial Nq. 361,544`

' (ci, 25o-11j 9 Claims.

The present invention relates to quadrantal error compensating mechanisms YwhichA effectl bearing correctionsfor radio direction indicators, and more particularly to novel multiple arrangementsfor selective compensation in a plurality of ranges of radio frequency reception.` v

To obtain accurate azimuthal bearing indications, radio direction finder systems are generally provided with a so-called quadrantal errorV compensator to mechanically correct deviationferrlr's 'of the indicator readings, over`360 of arc.` The errors are due to directional distortions of ther received radio Waves, inherent in the radioA installation. The bearing deviations usually are of the order of a few degrees, and in some instances may reach to 10 or even 20, depending upon the character and closeness of the surroundingfinei tallic objects.

^ It has been found that 4the quadrantalY,errors l20 tion. Thus, when operating on radiol vfrequencies depend upon the frequency range of radio( recepin widely separated reception bands, the correotions Were not fully reliable unless the corrector 'mechanism Was correspondingly rearranged or changed in the different ranges.VV vThe present invention permits such change to be eiected with a minimum of time and attention. 'This is particularly advantageous aboard an airplane.V

Quadrantal errors have been foundto depend ,upon the degree of draught of a shipl` in water. vThe invention is accordingly `also 4 applicable aboardship for readily accommodating th'e'jradio directional error draught. H It is the principalv object of thev present invenl corrections to the degree "of tion to provide quadrantalA error'correctorfarr-A rangements incorporating a plurality of corrector cams calibratedl for correspondingly' dierentreception bands, selectively,- placed intobperation by the mere twist of a knob or flip cfa. lever.

,The corrector vcams areA arranged adjacent each other. The associated'mechanism selectively erigages one camat a time. The numbenoicams yused depends on tliejfrequencyran'ge.orfbands over which theV systemgis to operate, andfmay Well'correspond to one-half or the"` full,v number of frequency reception 'bands of the direction' finder receiver. Each cam is individual1ycali-- brated to properly quadrantally compensate., for the radio bearing indications in the'associated band.

Further objects. advantages and capabilitiesl of .the invention Will become apparent inthe .following description of specific embodiments thereof Which: L

Fig. 1 is a schematic diagram of an automatic radio direction'finder systemincorporating the invention.V

Fig. z is,v :iiiy enlarge `iperspeiive 'View sho of a quadrantalerror compensator, section;` -f

cam.;-

Fig. 4' isa plan vievv*ofoneenibodimentoffthef I errors corrector rmechanism ,Y

multiple quadranta'l of the invention n f f Fig.A 5 isa vertical cross-sectionalfview l mechanism of Fig; 4i taken along'the linel ihereoffm Figigisa plan View ohf'ga/modiiiedformoflthe l,

'inveniienii Fig. 7 is along the line Fig.- 6."

ofthe-present invention.' Y Y *Fig. Q is a vertical cross-sectiorall View through` .y the vlmechanismv of8, takenfalong-theiline taken along Vthelin'eHl-F-Ill' of Fig. 4;"s'howing details ofthe camjselector thereof.Y i

` "Figari, 12 andisfiuustratedetaiisfoffth Caml j Figs:v 14,'.15 Land 16 show detailsofthefcam V; Vselector'of theembodimentillustrated,inFig. 7." Figari?, ligandi9.illustratedetailsof the-camy invention `Sheri/nin'Figs.*Sand 9.*

automaticradio i directionnder' system embodying the quadrantal errorcorrector mech-1 "anis'mbi the 'invention is; diagrarnnaticallyillus- 'f issued January19, 1943, and assigned to the-same uassignee as :the lpresent invention, A non-direc-y tionalfantenna'lf, anda rotatable directional o rl` "j locpantennaj 22 `shown in dotted lines streamline housing 23, are connected to the Y'raijlioi. frequency inputrf/'jdillection `iinderfzll"through lead. 2 In and `loopj cableV 24""respectively-j Ear' v phonesZ are Vfor the aural' determin'a'tionkof the. ,g station tuned-in; or for effectingjauralnull Y'di"-1; i

rectional' determinations.'

- An electric motor,` controlled throu'gh'cable 12H6 by direction findercircuitsZ; is arrangedvv'ithin i l `housiglgfor'directly rotatingv loop yantenna 22 i' f f inl a ,marinersuch' as ldisclosed in vthe copen'ding applcationreferred tc'ijandrf as will begdescribed; Y in more detail jhereinaftergf (A 360 alziniuth'al indicator 281s mechanically connected tol loop ..'ariiennazzlpy'afieximemehaiiiqaishafizs for vindicating the bearing positions oftheloop'ganjtenria atfa vremote location therefrom .suchjas Vnear the, pilot. -As3wil1belatershownythequad- :rantal errorcorrector mechanism enclosed Avi'fithin-r Figs is 'apiarifviewfof a caiibraieeygorfectef f1 f 9. Verticalrosssectioalpewztaken 1-,1 throughvthe mechanisme.

' electorf mechanism of I the embodiment i of i .y

` tive operation.

rotatable loop antenna 22 and indicator 23, whereby `the indications by indicator needle 30 trolley 42 and loop shaft 35. A cam follower 55 is secured at the pivotal region 48 in the form of an upwardly extending rod having aplurality on the dial of indicatorf28 are au'tornaticallycor'V rected to correspond tothe trueAvv geometricalv bearing on the radio station tuned-in.

The streamline housingv 23 is used where theloop antenna is mounted exterior of the body ofthe aircraft indicated at 3|. The quadrantal error corrector mechanism within housing 2T-` is,' in the illustrated embodiment,'mounted adja;;l

cent the loop antennaand against; the innerlsurface of the aircraft body 3|. 'I'he position of the quadrantal error corrector mechanism may, however, be remote from the loop antenna. Also, the

loop'motor may be positioned apart from the quadrantal error corrector mechanism, suchA as actually within thechassis of the direction finder receiver. A hinged cover 32 on quadrantal error` corrector housing 27 may be opened 'by meansuof locking nut t3i to permit accessto the corrector mechanism within Selective changes y in the quadrantal error corrector may Vvthus be directly effected. If the loop antenna isy in a Vrelatively inaccessible place, the correctorA mecha anism enclosed -in housing 21. is preferably sepf arate from the loop antenna, being placed nearer the operatorwho-may readilyeffect theselec- Reference is now made lto Fig. 2, the perspective illustration .off an operating section( ofthe quadrantal error corrector .'mechanism. The arrangement illustrated corresponds to the basic corrector assembly; incorporated in the quadrantal error corrector of my copending application.

Serial No. 344,854,1iledonJuly 11, 194D, for "Quadrantal compensators,` and assigned to `the 'same assignee as the present` case. It is to be l' Variat-iony tlfieradial'dispositicn of internal `camsurface'tdetermines the amount cf anof cam Contact lugs orfnilsf 55. pro-looting in different directions; Internally camnied' members l, 58 are spaced apart for individual engagement with one of the lugs 55, The internal cam -zsurface ivf-lyotcam 5ft is engaged with its associated camriollowerlug 56, to define the degree of radial entension.l of the trolley.

gular displacementleffective between shaft 35 and n carn, the. proper compensation. ot `the, readings understood, howevera thatthe present invention Y may be practiced with other equivalernt'` quadrantal error correcting arrangements, insofarl as the corrections, per se, arefeffected; in,- vention being more broadlygconcerned with the `multiple. arrangementsv and selective control of the compensator, Once aselectiontlis made, `the mechanism operates in-Y theusual `manner:toponopensate throughrcalibratedaction, asby acarn.

, .Shaft 35 is connecteddirectly to "the'loop an- ,.tenna; and is connectedfto central shaft 3550i the i mechanism throughilexible` coupling member 3l.

`The indicator 28 ismechanicallyconnectedto the mechanism. by, flehihlsehle 2.9 through hQfiZOh'- tally mountedshaft 38. A worm 40. i'sfsecured to shaft 38 'and'meshes with worm gear 4I; I'he frnechanical` engagement between .loop shaft 35 and. indicator shaftwis arrangedto be rigidyet relatively angularly displaceable under .the Icontrol of a cam.V A trolley 42, comprised offlink'ed arms 43, 44, 45 `and 46 is incorporated i'n the illustrated corrector mechanism.

` The trolley arms :arers'pectively linked atpiv'- otalpointsll'l,V 48 andAS. The free end "off arm 43 is adjustably secured`toI the upper end'of vertical shaft 3S; the free end of link 46,' being secured adjacent thereto tothe upper end of a 'sleeve 5l) concentric aboutv Vertical shaft 36.

grip the arms 43and 46' tothe shaft and"sleeve ends. The worm gear 4l isl mechanically'se.- cured to sleeve by suitable. set screws indicated tail hereinafter.

63is' the result offafsrn A 1 connecting the determinedicompenjsation errors plotted on blankY 53a" `Complete and accurate its. associated cam follower"nib.` 5.6 through the suitable actuationoffmeznberV y55.. The selective cam controlacton.wllbeidescribedin more de- As. many. individual corrector camsmay be. used: asis necessitated by the overalll radio. vreceptiony range ofthe system.,` and design reflnernent.4 *A 'A A typical calibrated, corrector cam isillustrated in plan View inElgQll .Tl'iefcam: blank $3` has an inscribed 366i graphgdesigned. to translate quadrantal error ,determinations `for the respective band. into. correction. curve, in adirect, accurate andfsmplemanner. A series of` concentric Vcircles 6K correspond to, `the)magnitude of the .quadrantal e'rr'orfin degrees.. Centrally disposed" circle $5y correspondsto zero. quadrantal error correction., The concentric circles radially larger than zero .cir-.cleA l 65. reiter to j a. `negative quadrantal error correction; the smaller ones, to

1a 1positive correction. V.lirjcuate radial lines B are' arranged'at lo',a separations-over 350"A of arc,

`tiein'gidesigned` in accordance with the geometrical law', of motion and" c'oacti'on ofthe cam fol'- lowers withvrespect to theinternal cammed-surface. Internalv camin *ejdjr surfacelof cam blank olc'itliA continuous curve quad'rantall error" vcompensation over the l,360"

azimuth is effecte'djby'gthe,mechanism of the inpresent for all indications;

Vention; being' automatically and continuously Y The-embodiment@ theinverltqnfuiustrateq in Figs. 4 andY 5v comprisesl four spaced cams 5'1', 58,

53 and 50; individuallycalibratedVv inL accorda-nce Awith the f qua-drantal errors ci" theassociated f-requencyV receptionbandsas previously` setforth.

VThumb screws 5I and'l52 are used to respectively v at 53, 53. A s/pring54.` is arrangedbetweilllinls '44 and istv to mechanically 'tiastne pivota'ipqit 48 between links 44 `and45 radially outwardly.

Rotation of shaftv 38.- ir1 either direction-causes ,a corresponding. angular displacement. .0?, the' Cam follower member 55 contains*V four`-v longtudi nally spaced: camiollower: nibsY fi'whicli are. ra-

. diallyfarrangedf: at;V 9.0.LIT separations.;` Only( one nib 56 ataitime may contact its associated cam; sur.- face.. `Ihefloopgmotori@is` positioned Within the -fquadrantal l'iousingy 27s,., as indicated atxfl. in dottedlines;` `Anf,electromagn'etic. clutcflll` couj ples motor'f'tonpinionp-IZ. Pinion 'ljyengages gear 13 which is vfastened to horizontaL rod 38 the loopantenna' occurs by suitable energization o `merx'iberl55to snapoveilpin-.l Dus't-.coveri32fof of motor "I and V'e'lectro'inagnretic 'clutch in'response to .radioV wave reception, .as described in detail in the said Patent No. 2,308,521.l The loop antenna drive occursuthrough4 gearing-112, 13,"and l 4|), 4| of the quadrantal error' corrector mecha.-

nism. Indicator 28 coupled tocable 291follows the angular orientation of the, loop antenna with proper compensation. through .the corrector mechanism. f H

The individual vcorrector are spacedly mounted by suitable posts bolted on sub-panel '16.' .Washers '|1.-predeterminedly spacel the cams from each other. x vSixzspaced bolts 13 are arranged about the periphery roflthe cams, holding respective posts 'l5I andwashers together. .Spring 54 mechanically vbiasesthe cam follower radially outwardlyY against the internal corrector cam surfaces, in afinannerdis-l closed hereinabove''in'.cormectioni.withv Fig. 2.-Y

.'Ihe particular `cam followernibf56fin position against its vassociated cam; controls the 'radial position of corrector trolley 42', in turn `effecting the proper quadrantal'errorl corrections on indicator 28 corresponding tothe frequencyband operated on. f

The selective operationl ofthe corrector system is performed by manually setting member 55. Fig. 10 -is an enlarged cross-sectional ydetail through the cam selector mechaniSm., The ,upper cam follower projection 56 is engaged with internal cammedsurfaceof upper cam. Follower member .55 is infdxedv mechanicalrelation with respectto trolley 42, through pin; 3| extending from trolley arm into a hole in the base of member 55. The, other nibs 56, being 90? apart withfrespect to the engaged'nib, donot interfere with thefree and normal operation of the engagedcam. A g

Fig. 11 shows the coaction of-projecting56 of followermember '55 with cammed surface 80 of cam 60. The varying `radial contourfo-finternal cammed surface80 ycontrols the" radial position of the trolley farms. Partiahsectionalview, Fig. 1'2, shows pin 8| extending, from'one of thetrolley arms, 45, for engagement withsettable cam followermember 55. v The openingsSZ in the base of member'- 55 correspond to the individual nibs 56 thereof, being selectively erenvgagev-y ablewithpinl.

The selective engagement of pin `3|`with,the respective -openingsBZ inthe bottom offollower member to effect selective cam .operation,'is.

performed manually by lifting member A55, away from pin 8| against the actionr of Vthe; internal spring 83 and then angularly rotating member 55until`a nib 56 4is 'engaged withfthe'desired one cams 57, 581,"597and v form the "selection fandthen the=corrector mechanism is 'rst opened-'to per;

locked with thumbnut33.'rv

rantal trolley 42 and` associated mechanical connectionsito the loop' antenna and indicator ofthis embodimentrare similar. to .that previously -Jd`e"- I scribed. A plurality :of individual'fcams 9I,` 92,' 93. and V94: are spaced one above the i other-by annular spacing rings '90, and areifheldgtogether bythe reduced diameter'sections 95,".95-ofl shafts 1 y 96, 96. Flat-headsfS'I, 91 are onthelto'psofsecllY tiohs95, 95. Shafts 96, 96 vare slidablysupported in elbows. 98, 98 projecting from frame 199. :A

compression spring v|00;is.concentric.aboutstheA y 'lower end of each shaft 96,'being'fbetweenthe lowermostisupporting elbow and an intermediate y collar |0| Von' the shaft. f l

. I. The fcam .assembly 9 I -tor94 accordingly 1sk 'l `r y mallybiased upwardly against two norinallyjs'ta.l

tionary'v cams |02, |02.-- "Cams |02, |02 are` are ran'gedionj rod I03`which is supported-:iniframe 99 across the top of the assemblyfand"haveindiev vi'dualcoaction with flat-heads .9.1, 191..'Rodf' |03 extends through housing .2.1. :A s'elector'handle |04 i'sf'secured'tothe projecting end` of camfrod |93.` The angularpositionof cams |02, |0-2 .;is altered through the rotation `of handlel 04.; When l four cams-are used, suchras .9| [to 94.Q illustrated;l

there are lfour corresponding positionsiefor handle |04. o f* j Fig." 15 is'anend viewl'of *the selectorhahdle 'andy associated. escutcheon f plate4 05 secured [on the kadjacentI side. wall :of housing,- v2l by` screws |06.. The'iourposition's,.'Nos. 1, 2, San'dl,y marked on plate .|05 .correspond respectively to the; operative engagement of respectivecams 9|,l 92, 9.3`and ftfwithfcam` follower lll'extending'ffrom' trolleyv 42. Io insure frigid andstable'po'sitioning fof. cams'A |02, |02 aftertheir'being set, holes|`01fare provided in escutcheonvplate |05 ,opposite/the f setting'lv positions, forengagngpn |08 `wllichis` spring biased'towardsplate |05. A knurledknob V|09 isat the outer end ofxpin1|08 fori proper manipulation. y

Y Fig.v 14 is a cross-sectional detailillustrating the coaction of a selectorcam |02 with`-cam as,- semblyjfQI `to194. Cams |02 and selector 'handle 104 of Figs. 6,1 7,14 andj'l'are in positonNoA, corresponding' to the .l engagement of corrector cam l94'wtl1l cam followerjll. ySprings |0|l,-'|00 Y V y pressi the cam assembly againstcams |02,- |021, o y whichfin position No; 4,'cause accuratepengage ment ofthe cam 94 withcam follower i0. VvUpon of the cams 51, 58,59', 60;;l A scale maybe marked for Visually ascertainingwhich"cam"and' nib `is engaged 'When kthe 'n upwardly 'displacing I*force on member 55 is released,'spring 83'sna'p`s it into position over pin'l", fi'xedly holdingI member 551 with respect to trolley 42. Internal'spring 83 is normally under compressioncoaxi'ally about rod 84, the bottom end of which is threaded into trolley arm 44. The upperend of spring`83 is concentric within knurledy thumb screw 86 and operable into'the top threadedopeningof mem.-A`

sageszitsassqciated camrfand. then..v ,releasing ydue cam`positioning, the Aselector cams |02, :|112` and` the cam assembly'remain stationary-.fthe operation of the quadrantalY error Tcorrector on...`

the vbearing :indicator of 'the system the'nfcor.- responding to the action of a single cam, namely the'oselected one. r`The remaining. cams stay outof coaction with the cam follower I9 and trolley.42.` YVl'hen selector` cams 1|02,`7|02 arerotatedto a new position, they press thecam assembly `9|x1to Y r 94 against'` the continuous spring action offcompression springs |00,- |00, to accurately select another'cam for coactionwith'cam follower` ||0L The dotted selector cam po's'ition1l02f of Fig. 14

:corresponds to position No.v 1,` vthe selection of l9| for coaction with the'c'am follower. `'Ih=.'dotted positions' of the Cam-assemblysl', szgqea', 94, v lcorrespond `to theirlowermost positionfin thev 'o ,i griech a`.n"ism.` Theintermediate`positions, Nos.2

Vforming a discontinuous arrangement To change from other in this mechanism inaccordance with the inventionis illustrated in'ligs.` 8 and 9. Four cam' sections areshown forselective coaction with cam follower mountedat the j'oiningof trolley arms 44,145. The respective cams lare in the formof split half sections pivoted upon post HE. Post ||6 isbolted onto sub-frameH by bolt ||1. The cam` sections are spacedfr'orn each other by lwashers ||8. `Corrector cam'units |2|, |22, |23,

|24 constitute the multiple corrector cam assembly for selective engagement with cam follower H5.` The. individual` corrector cam units, comprise two 180? sections ,of the previously described 360 internalcams. The cam units are indi--v viduallymounted onv semi-circular supports |2|', |22', |23,.|24 byscrews |25. Their effective cammed surfaces project radially inwardly from the associated semi-circular support members, insuring proper contact of the cams with cam follower ||5. c t

Toggle links |26 are attached'to the free ends of the cam sections, being pivoted onl ears |21v thereof. Each pair of links |26,'|26 of a cam set is pivoted in a yoke |28 ,securedito an individual selector bar |30. `Selector bars .|30 extend throughcorresponding Slots |32 (see Fig. 18) in housing 21, terminating in integral transverse handles |`3|. A compression spring |33 is arranged about each bar |30, positioned between housing 21 and yoke |28. Yokes |28 and toggle links. |26 are thus normally biased inwardly, whereby the cam units are normally in the inoperative position when'their selector bar ,|30 is Y in the inner position.. n I i v i To select va cam unit for active 4eoaction with follower. 5, the corresponding selector Vbar l|30 is Vpulled outwardly through its handle |3|.

Upper selector bar |30 attachedto upper cam.'

unit |2| is shown in the extended position, the

open housing lid. 3.2. The selected cam .V (corresponding to position No.1),'isnrst disengaged by rotating the verticallyprojectngf handle |3|V by 90" then pressing. .itfinwardly or 'releasing` it. to .permit its. spring` |3;3"toforce itA back to the neutral or inoperative position... -The cam thereupon spreads'aparttothe inoperative position. The selector 'bar (|30) Tof: the next desired cam is then pulled. outwardly: against its spring, to engage'the cam with the cam follower, in the manner.` previously described iniccn'nection' with.` cam unit 1.2L` y k;""" i A supporting and guidingfmemberMO is,` provided foreach half ofzthe cam assembly. Mem-l bers. .|40 contain :horizontalg projecting shelves |4'|,. |42,|4'3, |44ffor the respective `cam .units |2|,-|22, |23, |24'. A mountingV nflange |45 eX- tends at the bottom of members |40 for their securement to subfpanel 16 by screws/|46. The unpivoted or free ends of thesemi-circular supports |2|?, |22',"|2.3, |24 ,'contain1ugsx|4|, |42', |43', |44 which project `onto theshelves |4|, |42, |43, |44. The lugsA engage 'theshelves through pins |41 passing therethrough and terminating in shoulders or larger heads |48 which ride in corresponding slots in the shelves. The' 'cam supports |2|",\|22:,` |23', |24' are accordingly horizontally supported between pivotal 4post ||6^andtherespective members |40, |40. Also,the horizontal pivotal movements of thel cam sl'ippor-tsf are Y'guided by the shelves |4|,

, 142,143,144.of'member um. munis manner, the

cam thus .being in operative or active relation Y To holdselector` bar |30Yin with' follower l5.

the retracting action this outer position,` 4against of its spring |33, position. Recessed portion |34 of bar |30 is in this manner permitted to lock transversely against narrow horizontal slot |32 in housing. .21.

Figs. 17, 18 and 19 are enlarged detail sectional views-"more clearly illustrating the correlation of the respective selector yparts of this construction. Selector Vbars |30 are rotatably joined to their respective yokes |23 by an expanded head |35within the yokes. With the upper selected bar .|30 maintained'in thefextended positionpthe corresponding cam unit|2| is engaged,l a con-V tinuous 360 cam surface thereupon being effective on cam follower l5. The remaining three disengaged cams `(122, V|23, |24)A are pivoted ,apart to their normally inoperative relation,

itis twisted 90 into a vertical i.

wholly outpositions Y semi-circular cani units |2|, |22, |23, |24need notv be very strong structurally, but merely of sufficient strength to coactwith cam follower l5. The camsupports |2|, |22', |23', |24' in coaction with the' supporting and guiding members |40, |40 provide the necessary structural strength for the cam assembly while permitting free selective coaction ofthe respective cams. E

Although preferred embodiments of the invention are herein disclosed using four camsin the multiple cam assembly, diiferent numbers of cams may be used@ As will be apparent to those skilled inthe art, modifications and variations `in the constructional features and arrangements'illustrated may well be made, without departing from the broader spiritfand scopeof the invention as defined in the'following claims A Y ,What is claimed is:y 1 f 1. A quadrantal"error-@corrector foran indicator comprising:` arpluralityrof corrector cams with individual pre1-shaped cam surfaces; means mountng'-s`aid ,cams one next to another; a camrfollower corpledbetween theindicator and said cama'a member adjustably mounted on said cam"follower,"A said member havinga plurality of projections-..spaced in crresponiiencewith` the of saidc'ams; and `means for holding said 4member rin its adjusted kpositions on said cam follower for, selectively op'erating `said projectionsagainst a corresponding cam surface,

` one cam engagement to anarrangement, it is unnecessary to whereby selectivel quadrantal'error compensation is effected on saidindicatorby the corrector.

1 2. A quadrantal-error corrector comprising: a pluralitypf. corrector cams; .means spacedly monntinggsaid camsE one next to another; la cam follower member `having a plurality, of projections spaced in correspondence with the spacing of said: cams; pa.; followerfarm unit carrying said memberV at ai free fend thereof 1in coaction `with said camv surfaces; and mechanism for selectively operatingfsaidprojections against .their corresponding cam sur-faces. including a spring mechanically biasing said member against's'aid follower-arm unit, and an instrumentality for lock-` ing said member in the position on said unit whereby solely the selected projection engages with its corresponding cam surface. f

3. A quadrantal error corrector for a. direction nder comprising: a frame; a plurality of at corrector cams with individual cam surfaces preshaped in accordance with respective radio frespaced corresponding to the spacing of said cams;

and mechanism for holding said member in its adjusted positions on said cam follower for operating one of said nibs at a time against its corresponding cam surface, whereby selective quadrantal error compensation'is elected on the indicatorby the corrector. v 1` 4. A quadrantal error corrector for an indicator comprising: a plurality of corrector cams with individual internal cam surfacespre-shaped in accordance with respective radio frequency reception bands; means .spacedly mounting said cams one next to another; a cam follower member having a plurality of elements on the exterior surface thereof spaced in correspondence with 'the spacing of said cams and oriented in respectively diiferent directions; a follower-arm unit arranged within said cams and adjustably carrying said member for selective coaction with said cam surfaces, said unit being coupledl to the indicator; and mechanism for holding said member in its adjusted positions on said unit for selectively operating said elements against the corresponding cam surface to effect yselective quadrantal error compensation on the indicator.

5. A quadrantal error corrector comprising: a

plurality of corrector cams with individual internal pre-shaped camsurfaces; means i'lxedly mounting said cams one next to another; a cam follower member having a plurality of nibs on the exterior surface thereof, spaced in corresponds ence with the arrangement of said cams and oriented in respectively different directions; a

spring-pressed follower-arm unit carrying said member in coaction with said cam surfaces; and mechanism for selectively operating-said nibs against the corresponding cam surface including a spring mechanically biasing said member against said follower-arm unit, and an instrumentality for locking said member in position on said unit whereby solely the selected nib engages with its corresponding cam surface.

6. A quadrantal error corrector comprising: a plurality of corrector cams with individual cam surfaces pre-shaped in accordance with respective radio frequency reception bands; means spacedly mounting said cams one next to another; a tubular member having a plurality ofV elements on the exterior surface thereof, spaced in correspondence with the arrangement of said cams and oriented in respectively different 'directions; a spring-pressed leverage system carrying said member in coaction with said cam surfaces; and vmeans for selectively operating said elements against the corresponding cam surface including a post secured to said leverage system,

said, member being rotatably mounted on said post, a spring mechanically biasing said member against said leverage system, and an instrumentality for locking said member in position on said ment leverage system whereby solely the selected ele--` engages with,v its corresponding 'cam surface; A, 7. A^quadrantal error corrector comprising: a,` pluralityk of corrector cams with individual preshapedlcam surfaces; means'fixedly. mounting said cams one next to another; a tubular mem-1 l ber having a plurality of nibs spaced in correl spondence'with the :arrangement .ofv said cams; a spring-pressed trolley arrangement for connectionr between a', directional antennal andinn dicator `carrying said member at 'a Afree end thereof in coaction with said cam surfaces: andl meansV for selectively operatingvsaid nibs against the corresponding cam Vsurfaceincluding a post secured to said trolley arrangement and extending transversely of the mountedcams, said member being rotatably mounted on said postya compression spring within said member and about said post for mechanically biasing said member against said trolley arrangement, and an instru-VK mentality for locking said member in position on n said trolley whereby solely the selected vnib engages with its corresponding cam surface.

` 8. A quadrantal error corrector comprising: va plurality of corrector cams withV individual camV surfaces pre-shaped lin accordance with respec-- tive radio frequency *reception bands; means kspacedly mounting said cams onev next tolanother;'a tubular member having a plurality 'of'.v projections on the exterior surface; thereof, spaced in correspondence. withrthe spacing f. of said cams and oriented'in respectively .dii-ferent directions; a spring-pressed follower-armunit carrying said member in coaction with' said cam surfaces; and mechanism for selectively` operating said projections againsta correspondingg` A cam surface including a post securedtofsaid fol-7` lower-arm unit, said member .being rotatably l mounted on said post, a compression spring 'me-r lchanically biasinglsaidl member against said folloWer-armunit, and an instrumentality for locking said member in position on said unit whereby f `having a plurality of nibs on the exterior surface j thereof, spaced in correspondence with the spacing of said cams and oriented in respectively different directions; 'a follower-arm unit arranged withinsaid cams and carrying said member in coaction with said cam surfaces; and mechanism for selectively operating said nibs against a cor-A responding cam surface including a postsecured` to said follower-arm unit and extending'ftra'nsversely of the mounted cams, said member being rotatablymounted on said post, a springmeo chanically biasingl said lmember against said fol-l lower-arm unit, and an instrumentality for lock-` ing said member in Aposition on said unit whereby solely the selected nib engages with its corre-H sponding cam surface; and a knob extending above said member, concentrically aboutl said` post, for manually controlling the member locking by said instrumentality.` 1 f l .y 

